Rolling mills

ABSTRACT

A rolling mill is provided having a roll line made up of a plurality of successive three roll stands, each defining a pass, which line includes at least two sizing passes disposed beyond a row of flat passes, the rolls of each sizing pass having sizing grooves shaped so that the reduction in cross section of the work in the pass defined by the sizing grooves is at an analytical minimum when the work is in a non twisted state between passes.

United States Patent [1 1 Bindernagel et a1.

ROLLING MILLS Inventors: A11 Bindernagel,

Dusselfdorf-Oberkassel; Werner Demny, Dusseldorf, both of GermanyFriedrick Rocks, Dusseldorf, Germany Filed: July 14, 1971 Appl. No.:162,499

Assignee:

Foreign Application Priority m July 7, 1970 Germany P 20 35 482.9

US. Cl. 72/234, 72/224 Int. Cl B2lb 13/08, B21b 13/10 Field of Search72/234, 235, 224

References Cited UNITED STATES PATENTS 2/1971 Cofer..; 164/76X Aug. 28,1973 3,380,278 4/1968 Dilling 72/224 3,243,983 4/1966 Norlindh et a172/235 3,618,354 11/1971 Bindemagel et a1... 72/224 3,643,488 2/1972Bretschneider 72/191 Primary Examiner-Milton S. Mehr Attorney-Eugene F.Buell et a1.

[57] ABSTRACT A rolling mill is provided having a roll line made up of aplurality of successive three roll stands, each defining a pass, whichline includes at least two sizing passes disposed beyond a row of flatpasses, the rolls of each sizing pass having sizing grooves shaped sothat the reduction in cross section of the work in the pass defined bythe sizing grooves is at an analytical minimum when the work is in a nontwisted state between passes.

4 Claims, 3 Drawing Figures Patented Aug. 28, 1973 3,754,425

lnvenlars. 422'22' axmgyez ,2

ROLLING MILLS This invention relates to rolling mills and particularlyto sizing passes for small-section rolling mills, such as wire rollingmills, having three-roller passes of which at least two sizing passesare provided beyond a row of flat passes.

In previously proposed rolling mills of this kind, a plurality of roundpasses for sizing directly follow a row of flat passes, all the passesin the row being alternately angularly offset relatively to one anotherby half the pitch angle between the roller axes. To enable thework-material to be broadened, the round passes are open towards theroller gap, the size of the opening becoming smaller towards the lastpass. The workmaterial emerges from the last flat pass in the form of ahexagon whose cross section has three short sides and three long sidesin an alternating order. The three long sides of the hexagonal crosssection are produced by the working surfaces of the rollers of the lastflat pass, while the three short sides are formed by slight underfillingof the pass in the region of the gaps. When the work-material, providedwith this cross section, enters the first sizing pass, there is the riskof the workmaterial twisting between passes such that the short sides ofthe cross section lie in the pass openings located in the region of thegaps. Similarly, there is the risk of the work-material twisting by halfa pitch angle between the individual round passes, so that the portionof the cross section, which has passed through the opening in thepreceding round pass, again lies in the angularly offset opening in thenext pass. This results in a surface finish marred by ribs which impairfurther processing. Moreover, twisting of the work-material results in anon-circular finished cross section, and the wear on the rollers isincreased by non-uniform progress of the work-material through thepasses.

Attempts have been made to prevent twisting of the work-material bymeans of additional guides, although this measure does not always act ina reliable manner and it is also expensive.

A feature of this invention is to design the calibrating passes suchthat stable, twist-free guidance of the workmaterial is ensured.

In accordance with the invention, the pass grooves in the sizing passesare so designed that the reductions in cross section achieved in thesaid passes are an analytical minimum when the work-material is in thenonturned state.

In rolling mills according to. this invention, the cross section of thework-material is always placed in the following pass in the position inwhich it receives the minimum reduction in cross section, i.e. itprogresses through the passes without twisting.

A large number of shapes are possible for the pass grooves in therolling mill according to the invention. Preferably, the rollers formingthe sizing passes have conic profiles which are disposed symmetricallyof the bottom of the pass groove and which, alternating from pass topass, have in the bottom of each pass groove a radius of curvature whichis alternately greater and less than the distance between the centre ofthe pass and the bottom of the pass groove.

The rollers can be readily provided with conic profiles by means oftools which may be manufactured by appropriate grinding of round steel.

Alternatively, the rollers of the last but one sizing pass or, if fouror five sizing passes are provided, the last but three of the sizingpasses, may have an arcuate profile whose radius of curvature is greaterthan the distance between the centre of the pass and the bottom of thepass grooves. The arcuate profile has the advantage that it is thesimplest of all conic profiles to produce. However, the uneven numberedsizing passes, i.e., the last sizing pass and, if provided, the secondfrom last and the fourth from last sizing passes, have to be formed byrollers whose profiles have a curvature composed of different radii ofcurvature, for example an elliptical curvature, the radius of curvaturelocated in the bottom of the pass groove being the small circle. If aneven number of sizing passes is provided, the first sizing passfollowing the row of flat passes may be disposed without angulardisplacement relative to the last pass in the row of flat passes.

However, when there is an even number of sizing passes and the firstsizing pass has to be angularly offset relative to the last pass in therow of flat passes because of the arrangement of the roller drives, thelast flat pass maybe provided with a comparatively slight reduction suchthat, in the hexagonal cross section resulting in the said flat pass,the three sides of the hexagon abutting against the rollers are theshorter.

Alternatively, however, the rollers of the last sizing pass may have anarcuate profile whose radius of curvature must, of course, be smallerthan the distance between the centre of the pass and the bottoms of thepass grooves.

In the foregoing general description of this invention certain objects,purposes and advantages have been set out. Other objects purposes andadvantages will be apparent from a consideration of the followingdescription and the accompanying drawings, in which:

FIG. 1 diagrammatically illustrates the last pass in a row of flatpasses in a rolling mill in accordance with the invention,

FIG. 2 diagrammatically illustrates the first of two sizing passes inthe rolling mill, and

FIG. 3 diagrammatically illustrates the second or last sizing pass.

In the embodiment illustrated in the drawings, successive passes in arolling mill, e.g., a rod mill, are defined by three-roller standsarranged in a line with the passes, are alternately angularly offsetrelatively to one another by half a pitch angle, i.e., half the anglebetween the roller axes. Two sizing passes are provided beyond a row offlat passes. The hexagonal cross section work-material emerging from therow of flat passes being rolled in the two sizing passes to asubstantially round profile. The rollers are disc-like and in eachstand, the three rollers are arranged with their axes at v to oneanother.

The last pass 10 of the rowof flat passes is formed by three disc-likerollers 4, 6 and 8, whose perpheries only are shown and the strand orwork-material leaves the last pass 10 with a hexagonal cross sectionwhich has three equal short sides and three equal long sides inalternating order. The long sides of the hexagonal cross section areproduced by the rollers 4, 6 and 8 defining the pass, while the shortsides are produced by slightly under-filling the pass between therollers in the region 7 of the gaps 9 formed between adjacent rollers.

The first sizing pass 12, illustrated in FIG. 2, is arranged immediatelybehind the last pass 10 and is formed by three rollers 14, 26 and 18each of which has a pass groove with an arcuate profile. The radius 20of curvature of the roller profile is greater than the distance 22between the centre 24 of the pass and the bottom 26 of the pass groove.

The first sizing pass, which is the last pass but one, is disposedbeyond the row of flat passes such that the long sides of thework-material 2 of hexagonal cross section abut against the arcuateprofiles of the rollers 14, 16 and 18 while the short sides of thehexagon run into the pass 12 in the region of the gaps 9 located betweenadjacent rollers. In the illustrated embodiment, the first sizing pass12 is not angularly offset relative to the last pass in the row of flatpasses. The cross section of the work-material running through thesizing pass 12 is subjected to the minimum of deformation so long as itruns through the pass 12 in a non-twisted state.

Referring to FIG. 3, the second or last sizing pass 34 formed by therollers 28, 30 and 32 is angularly offset relative to the precedingsizing pass 12 by half a pitch angle, i.e., by 60 the pitch angle beingthe angle between the normals to the roller axes. The profiles of thepass grooves of the rollers 28, 30 and 32 forming this pass have anelliptical curvature which is symmetrical about the bottom of the passgroove. The shape of the ellipse is such that the radius 36 of the smallcircle at the bottom of the pass groove is less than the distancebetween the centre of the pass and the bottom of the pass groove, theradius of curvature of the bottom of the pass groove corresponding tothe small circle radius 36 of the ellipse.

When the last sizing pass 34 has such a configuration and is in thisposition, the reduction in the cross section of the work-material isagain at a minimum so long as the work-material is in the non-twistedstate, whereby the work-material is effectively prevented from twistingeven in the last sizing pass.

In another embodiment (not illustrated), three sizing passes areprovided. In this case, the first sizing pass is angularly offset byhalf a pitch angle relative to the last pass in the row of flat passes,which might be more advantageous with respect to the arrangement of thedrive mechanisms for the rollers and the direction of rotation, and,like the last sizing pass 34 illustrated in the drawings, has ellipticalprofiles in which the small circle of the ellipse is located in thebottom of the pass groove. The configuration and arrangement of thefollowing sizing passes may be the same as in the case of the passes 12and 34 of the previously described embodiment.

In a further embodiment (also not illustrated in the drawings), twosizing passes are provided as in the case of the grooving illustrated inthe drawings. However, as

a result of a given drive mechanism for the rollers, the first sizingpass, which has the same configuration as the pass 12 illustrated inFIG. 2, has to be angularly offset by half a pitch angle relative to thelast pass in the row of flat passes. In this case, the last pass in the.row of flat passes has to be designed such that only a slight reductionin the cross section of the work-material is effected in this pass. Thethree sides of the hexagonal cross section of the work-material abuttingagainst the rollers thus remain shorter than the three sides of thehexagon facing the gaps between the rollers. In such a case, thereduction in the cross section is again a minimum in the first andsecond sizing passes when the work-material is not turned or twisted.

In the foregoing specification certain preferred embodiments andpractices of this invention have been set out, however it will beunderstood that this invention may be otherwise practiced within thescope of the following claims.

What we claim is:

l. A rolling mill comprising a roll line having a plurality ofsuccessive three-roll stands each defining a pass line including a lastflat pass intermediate the ends of the pass line having rolls with meansto roll metal stock into a generally equilateral triangle having equallytruncated apices at all angles, at least two sizing passes disposedafter said last flat pass, the rolls of a first sizing pass havingarcuate sizing grooves so shaped that the radius of curvature at thebottom of the groove is greater than the distance between the axis ofthe pass and the bottom of the groove and the rolls of a second sizingpass having arcuate sizing grooves shaped so that the curvature of thegrooves is elliptical with the radius of curvature at the bottom of thegroove being a smaller circle and being less than the distance betweenthe axis of the pass and the bottom of the arcuate groove, said rollersof said first and second sizing passes being offset relative to oneanother by half a pitch angle.

2. A rolling mill as claimed in claim 1, wherein a plurality of firstand second sizing passes are provided.

3. A rolling mill as claimed in claim 2, in which the number of sizingpasses is even and in which the rollers of the first sizing passfollowing the row of flat passes is angularly symmetrical relative tothose of the last pass in the row of flat passes.

4. A rolling mill as claimed in claim 2, in which the number of sizingpasses is even and all the stands are positioned in the line with; therollers in adjacent stands angularly offset relative to one another, andin which the last flat pass is dimensioned to effect section transversea reduction of a metal stock having said truncated apices transverse tosaid rollers.

l I" I =0 8 UNITED STATES PATENT OFFICE v CERTEFICATE 0F CORRECTIONPatent No. 3 754 425 Dated August 28 1973 Inventor(s) Ali Bindernageland Werner Demnv rs in the above-identified patent It is certified thaterror appea by corrected as shown below:

and that said Letters Patent are here line 49 after "with" delete theman 4 Col 4' Clalm "effect" delete semicolon; I lines 51 and 52 after-section transverse-.

Signed and sealed this 18th day of December 1973.

(SEAL) At'test:

RENE D. TEGTMEYER Attesting Officer

1. A rolling mill comprising a roll line having a plurality of successive three-roll stands each defining a pass line including a last flat pass intermediate the ends of the pass line having rolls with means to roll metal stock into a generally equilateraL triangle having equally truncated apices at all angles, at least two sizing passes disposed after said last flat pass, the rolls of a first sizing pass having arcuate sizing grooves so shaped that the radius of curvature at the bottom of the groove is greater than the distance between the axis of the pass and the bottom of the groove and the rolls of a second sizing pass having arcuate sizing grooves shaped so that the curvature of the grooves is elliptical with the radius of curvature at the bottom of the groove being a smaller circle and being less than the distance between the axis of the pass and the bottom of the arcuate groove, said rollers of said first and second sizing passes being offset relative to one another by half a pitch angle.
 2. A rolling mill as claimed in claim 1, wherein a plurality of first and second sizing passes are provided.
 3. A rolling mill as claimed in claim 2, in which the number of sizing passes is even and in which the rollers of the first sizing pass following the row of flat passes is angularly symmetrical relative to those of the last pass in the row of flat passes.
 4. A rolling mill as claimed in claim 2, in which the number of sizing passes is even and all the stands are positioned in the line with; the rollers in adjacent stands angularly offset relative to one another, and in which the last flat pass is dimensioned to effect section transverse a reduction of a metal stock having said truncated apices transverse to said rollers. 